Designing an Efficient Power/Control System for a Network of Piezoelectric Speakers

Abstract

Extremely flat and flexible piezoelectric speakers have recently been invented, and one of their potential applications is in directional speakers. If a network of these speakers is hidden in the walls, each speaker’s signal can be phase shifted individually such that the sound cancels in some parts of the room and is amplified in others. Driving 16-64 high voltage speakers with individual signals requires a control system and amplifier that is as energy efficient as possible. To effectively manage so many analog channels, a multi-channel DAC was paired with a microcontroller and SD card and read out precalculated low-voltage signals for each speaker. An amplifier was then designed to boost these signals high enough to drive the speakers. Two designs were explored here: a common-emitter paired with a class AB amplifier, and a class D amplifier. Although testing was limited due to an unsuccessful 200V power supply design, the class D amplifier was found to be the more efficient solution with a wider voltage range. However, the class AB amplifier was much simpler and took up less space.